Together with its predecessor the 500K, the magnificent Mercedes-Benz 540K was arguably the most noteworthy production model offered by the Stuttgart firm during the 1930s, representing the pinnacle of its pre-war achievements. A development of the 500K, whose independently suspended chassis it shared, the 540K was powered by a 5.4-litre supercharged straight-eight engine. The 540K was one of the first models developed under Mercedes' new chief engineer, ex-racing driver Max Sailer, successor to Hans Nibel, who had died in November 1934 aged only 54. It featured the company's famous Roots-type supercharger system in which pressing the accelerator pedal to the end of its travel would simultaneously engage the compressor and close off the alternative atmospheric intake to the carburettor. This system had been thoroughly proven on the preceding series of Dr Porsche-conceived S-Type cars, and in effect the 540K was the last supercharged production Mercedes until relatively recent times.
Launched at the Paris Salon in October 1936, the 540K had an engine that developed 115bhp un-supercharged or 180bhp with the compressor engaged. The gearbox was a four-speeder, but with a direct top gear rather than the overdrive ratio used on the earlier 500K. With the supercharger engaged, the 540K's blown straight-eight gave it a top speed approaching 110mph (177km/h) matched by servo-assisted hydraulic braking. Its performance potential was such that Mercedes-Benz in the UK retained racing driver Goffredo 'Freddy' Zehender as technical adviser and demonstration driver, since the super¬charged Mercedes was one of the few genuine 100mph road cars available in the 1930s.
Tested by Britain's Motor magazine, the 540K was judged to have less heavy steering and handling than its predecessor, the 500K, plus an even more comfortable ride, even though the same all-round independent suspension layout with parallel links and coil springs at the front and swing axles at the rear was retained. The Motor's test car returned 102mph over the timed quarter-mile with the supercharger engaged and 85mph with it disengaged. Such performance was achieved at the cost of 11mpg petrol consumption, but the servo-assisted brakes came in for fulsome praise, the blower was found to be relatively quiet, the springing more comfortable than that of the 500K, and the steering and handling also compared favourably with that model.
In May 1938, the 540K was tested by Motor's rival magazine Autocar and achieved the highest maximum speed of any road-test car up to that date: carrying three pas¬sengers, the car reached 104.65 mph (168.5km/h) on the race circuit at Brooklands, Surrey. 'One's foot goes hard down, and an almost demonical howl comes in,' reported test driver H S Linfield. 'The rev counter and speedometer needles leap round their dials: there is perhaps no other car noise in the world so distinctive as that produced by the Mercedes supercharger.'
Late in 1938, a revised 540K made its appearance, with oval-section chassis tubes instead of channel frame members, while the adoption of sodium-cooled valves followed the company's highly success¬ful racing practice.
Although the 500K/540K chassis attracted the attention of many of the better quality bespoke coachbuilders of the day, the company's own Sindelfingen coachwork left little room for improvement. The cabriolet came in a variety of styles and this right-hand drive example has the Cabriolet C option, which offered four-seater accommodation allied to breathtaking performance. The bulk of 540K production was destined for the home market but factory records show that chassis number '169312' was produced in November 1937 and delivered new to Messrs Campbell Symonds & Co in London, England. '169312' was finished in black, as it is today, and was first registered in January 1938 to a Captain Rethymnia with the UK registration 'HMF 419'.
The 540K subsequently left for the USA and was re-imported into Europe in 1997, remaining in the immediately preceding owner's care for the next 12 years. Restored to a high standard at date unknown, the car is finished in its original colour combination of black with red interior, the latter boasting deep wool carpets and beautiful wood veneers, and is presented in superb condition. Mercedes Classic has kindly confirmed that this rare and desirable 540K Cabriolet C retains matching numbers, and the car has been with the Italian Mercedes-Benz registry since 1998 carrying number '252'.
The manufacturing record of the 540K reveals its exclusive nature: 97 being produced in 1936, 145 in 1937, 95 in 1938 and 69 in 1939 before the war ended series production (though three more were built up to July 1942). In recent years, the rarity, style and performance of these big supercharged Mercedes have made them one of the most sought-after of all classic cars on the few occasions they have come on the open market.
Representative of the very best that money could buy in the late 1930s, this car is an excellent example of this classic German model.

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